Thanks for checking out the game! Hmm.. the video you show does look a little buggy. It is not supposed to look like that. Try it on https://up-n-up-game.herokuapp.com/ to see if it's because of the embed in itch?
na the same thing happened. could it be something with the time scale? cause usually lighter games run at like 300 fps on my pc and it might be messing up whatever technique you are using for collision. try capping the fps if you haven't already. and have a look into the collision code for anything that might be effecting the rate at which tests for collision take place .